This application is based upon and claims the benefit of priority from the prior Japanese Patent Applications No. 11-194459, filed Jul. 8, 1999; and No. 2000-166195, filed Jun. 2, 2000, the entire contents of which are incorporated herein by reference.
The present invention relates to an endoscopic high-frequency knife. Such a high-frequency knife is typically inserted trans-endoscopically into a body for dissecting tissues such as duodenal papilla.
Conventionally, a high-frequency knife for dissecting a diseased portion in a cavity by using a high-frequency current has been known. An example of such high-frequency knife is disclosed in Jpn. Pat. Appln. KOKAI Publication No. 9-285472, Jpn. Pat. Appln. KOKAI Publication No. 4-364836, and Jpn. Pat. Appln. KOKAI Publication No. 5-176940 or the like, for example. Generally, such a high-frequency knife has a conductive wire inserted in a flexible sheath, and this wire is exposed to an external wall surface at a tip end portion of the sheath. When a surgeon pulls the wire, the tip end portion of the sheath is bent, whereby an exposed wire portion is tensioned, and a dissection portion is formed. When this dissection portion is brought into contact with a diseased portion, a high-frequency current is supplied to the wire, whereby the diseased portion can be dissected.
Generally, such a high-frequency knife disposes a dissection portion according to a state of the diseased portion in a cavity, resulting in a complicated structure. For example, in the duodenum, in the case where an exit of a bile duct carrying bile to the duodenum is narrowed by a tumor or stone and the like, it is known that a papilla sphincterectomy (hereinafter, referred to as EST) for dissecting a sphincter that is present at a distal end of the bile duct is performed. In this EST, since the pancreas is positioned on the right side of a site to be dissected, it is desirable that the dissection portion of the conductive wire of the high-frequency knife be positioned at the left side opposite to the pancreas when the sheath tip end is seen from the proximal end.
When using the conventional high-frequency knife, the following undesirable situation very often occurs. That is, in the case of the high-frequency knife described in Jpn. Pat. Appln. KOKAI Publication No. 9-285472 that is the above prior art, a direction control plate for controlling an orientation of the knife extends from a tip end portion of the sheath to the vicinity of the proximal end thereof, and a relative rotation along a longitudinal axis between this direction control plate and the sheath is restricted, whereby the tip end can be easily rotated from the proximal end of the sheath. However, in this high-frequency knife, its configuration and operation become complicated. As for the configuration, the number of parts is increased, and the assembling process becomes complicated because the direction control plate and means for restricting this rotation are required, whereby parts cost and assembling cost are increased. As for the operation, a complicated operation for rotating a dissection portion of this high-frequency knife to a predetermined position after the high-frequency knife has been inserted into the nipple portion must be performed.
In addition, in the high-frequency knife disclosed in Jpn. Pat. Appln. KOKAI Publication No. 4-364836, a complicated direction control means for restricting a curved direction is provided at the sheath. Further, in the high-frequency knife described in Jpn. Pat. Appln. KOKAI Publication No. 5-176940, there are provided a plurality of wires for restricting a curved direction, whereby the number of parts is increased, and the assembling process becomes complicated. Therefore, in these high-frequency knives, there will occur a problem similar to the aforementioned problem that parts cost and assembling cost are increased.
The present invention has been made in view of the foregoing circumstance. It is an object of the present invention to provide a high-frequency knife which has an extremely simple structure and which is capable of reliably orienting a dissection portion in a desired direction.
In order to achieve the foregoing object, according to the present invention, there is provided an endoscopic high-frequency knife comprising: a flexible sheath inserted into a body; and a conductive wire inserted into the sheath; wherein the sheath has a tip end portion at which a part of the wire is exposed to an external wall surface; wherein the tip end portion is bended by pulling and pushing the wire; and wherein an exposed wire portion is tensioned, thereby forming a dissection portion. This high-frequency knife comprises: two grooves which are punched at the external wall of the sheath along a longitudinal axis and to be spaced each other, the grooves causing the wire to be exposed to the external wall surface; a sheath longitudinal central plane which passes through the two grooves and a fixing section which is provided at the tip end portion of the wire and fixed along the longitudinal axis of the sheath; and a guide arm section formed by bending a portion adjacent to the fixing section. The guide arm section is disposed at a tip end groove of the two grooves, and the wire portion exposed to the external wall surface is overhung laterally of the longitudinal central plane at the tip end of the wire portion.
Thus, according to the present invention, an endoscopic high-frequency knife which has an extremely simple structure and which is capable of reliably orienting a dissection portion in a desired direction can be obtained. Further, the structure of the guide arm section both makes it difficult to slip off a knife wire from the sheath, and. makes it possible to smoothly dissect the desired site.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.